The problems began at around 10 a.m. US Eastern Time

The problems began at around 10 a.m. U.S. Eastern Time and hadn't been resolved by early afternoon, according to information posted by Microsoft on its Live Status page.

The Outlook.com issue is preventing affected users from seeing all their email messages. There is also a related problem with the People contacts application in which address book change notifications may not be properly delivered to Hotmail. This is causing some customers to have out of date contacts on Outlook.com.

There are no details on what affected SkyDrive users are experiencing.

Microsoft is promising an update on the problems by 2 p.m. It's not clear how many people are affected.

A spokesman for Microsoft said via email that the problems are affecting "a small number of customers' access" to some features of the impacted products. "We are working to restore full access to the services as quickly as possible," he said.

The problems come days after Microsoft last week triumphantly announced that it had exceeded 99.9 percent uptime in each of the past four quarters for its Office 365 cloud suite, which businesses use for email, collaboration and communication.

Microsoft also said last week that it will report uptime stats for the Business, Government and Education editions of Office 365 at the end of every quarter from now on. Until now, only Office 365 customers have had access to that type of availability information.

The Office 365 components measured for uptime are Exchange, SharePoint, Lync and Office Web Apps. Some industry analysts welcomed the move towards more transparency, but said at the time that Microsoft should go further and provide more granular details, such as uptime by geography and by application, and ideally even set up a public status page like the Live Status page it has for consumer cloud applications.